Abstract: A distributor that supplies either a liquid or a gas to a bed of granular media, such as a sand filter, is divided by inclined interior walls into primary and secondary horizontal conduits that extend parallel to each other. Gas metering orifices are positioned at an intermediate level in the inclined walls and liquid metering orifices are positioned beneath the gas metering orifices in the inclined walls. A liquid or a gas is supplied to the primary conduits, passes through the metering orifices into the secondary conduits, and through dispersion orifices in the secondary conduits into the filter bed. At least some of the secondary conduits are each connected to at least two primary conduits so that liquid can flow from one primary conduit through a secondary conduit to another primary conduit to compensate for inequalities of flow along the primary conduits.